“He energized the Democratic base, which was disillusioned after President Obama’s debate performance last week,” said Aaron Kall, director of debate at the University of Michigan. “At the very worst for him, the debate was a draw.”

Both sides claimed victory after the 90-minute encounter at Centre College — and, indeed, both tickets have reason to be pleased. Neither candidate committed a headline-grabbing gaffe and both nominees spoke in carefully modulated soundbites that will appeal to their parties’ core supporters.

“Traditionally, vice presidential debates don’t have too much of an impact on the overall shape of the race,” said David Lanoue, a political scientist at Columbus State University in Georgia. “And this one probably won’t either.”

Both candidates’ performances exceeded public expectations. A CNN/ORC International poll conducted immediately after the debate found that 55 percent of viewers said Biden exceeded their expectations, while 26 percent said he did worse than expected. For Ryan, 51 percent said he did better than anticipated, while 19 percent were disappointed. Overall, 48 percent of viewers called Ryan the winner and 44 percent picked Biden.

Undecided voters “probably were not convinced” by the debate, said independent pollster John Zogby. “But Biden hit the right notes for Democrats who were scared and saw their clear lead nationally and in battleground states evaporate after the Oct. 3 debate. He stopped the bleeding. Ryan, for his part, showed he deserved his place on the ticket and held his own.”

The debate was a contrast in style and substance. While Biden attacked Republican vice presidential candidate Paul Ryan on issues ranging from tax cuts to Iran, the Wisconsin congressman appeared cool and unconcerned. He gave no ground and occasionally counterattacked. In response to Biden’s attacks on his proposals for Social Security and Medicare, he declared, “This is what politicians do when they don’t have a record to run on.”

The vice president showed little respect for his opponent, 27 years his junior. He grinned, chuckled and shook his head at what he called the “malarkey” being spewed by Ryan.

“It looks dismissive,” said David Worth, director of forensics at Rice University. “If three words into the response he’s already shaking his head, he’s not listening.”